"Include what you use" for tests

Many of these tests implicitly required the target language library files to include the headers upstream.

Examples/test-suite/li_cdata.i

@@ -5,4 +5,8 @@
 %cdata(int);
 %cdata(double);
 
+%{
+#include <stdlib.h>
+%}
+
 void *malloc(size_t size);